THE PROBLEM
As part of the refurbishment and extension of the sulphuric acid bund a new chemical resistant bund lining was required to protect the concrete and contain leaks in the event of a spill or leak. Due to the concentration of the acid being stored within the tanks a highly chemical resistant bund lining solution was required.
SOLUTION
We proposed the application of a well proven and tested glass flake reinforced vinyl ester bund lining from our Partners Chemco International as the most suitable protective coating for this application.
Initially all concrete surfaces were prepared by method of vacuum controlled diamond grinding to remove surface laitance and contaminants, ensuring excellent adhesion of the new bund lining.
The corroded steel legs were prepared to ST2 using needle guns and tungsten carbide scrapers. This was followed by the application of a rust stabilising epoxy primer – Corroless EPF. This material is specifically designed to be applied to hand prepared steel, containing mined pigments that convert corrosion present to stable iron oxides such as magnetite.
The walls were treated using a cementitious fairing coat to fill blow holes in the concrete. This is essential when undertaking bund lining works as blow holes cannot be filled with paint alone! Failure to fill this blow holes would result in an unsealed surface, negating the purpose of conducting the bund lining works.
During preparation the diamond grinding lots of shrinkage cracking was exposed in the concrete slab. To remedy this the cracks were expressed using a vacuum controlled floor saw and repaired using a low viscosity epoxy resin.
Applying a liquid damp proof membrane
Due to the short time period between the casting of the concrete and application of the bund lining it was not possible to reduce the moisture content of the concrete to a point which would be acceptable for the application of a vinyl ester bund lining direct to the concrete. To overcome this a liquid damp proof membrane was applied in the form of two coats of a damp tolerant epoxy primer. Quartz aggregate was scattered into the second coat of primer to form a bonding bridge between the otherwise incompatible vinyl ester and epoxy coatings.
As per best bund lining practice a cove was installed at the floor/wall intersection in order to spread this potential point of movement.
Chemo International RB364 was then applied in three coats of contrasting colour as per best bund lining practice to a thickness of 1200 microns as recommended. Chemco RB364 contains self leafing glass flake which laminate within the coating film to provide a more tortuous route for aggressive chemicals to reach the substrate.
To ensure a seamless bund lining that integrity of the new coating was checked using a DC holiday spark tester, with any pin holes found marked with chalk prior to touching in by brush.
